Al over at "Beyond the Black Gate" is musing about what 5e will look like. I'm in agreement with sinclair’s opinions stated in the comments. Hasbro will license the table-top game to a 3rd party (won't be Paizo, since that would mean killing the Pathfinder goose which lays for them golden eggs) while retaining the "all-important" IP (which nobody has managed to monetize successfully). Some time afterwards, they'll possibly take another stab at licensing computer games.
Exactly what form fifth edition will take after that will heavily depend on who picks the game up. However, this hobby is chock full of "lessons learned" from the past. Most of this conventional wisdom is a load of hokum. Remember when everybody knew that boxed sets had killed TSR? The current conventional wisdom is likely just as accurate, and just as firmly believed.
So, in spite of the company that wins the rights to the pen-and-paper version of D&D quite probably having gotten their start as an OGL d20 company, they will probably adhere to the belief that a glut of substandard third-party material killed 3.0. Whatever licensing agreement we do see will likely fall somewhere between the OGL and its ugly 4e sibling. We'll also likely see stronger adherence to the traditional assumed setting of the game; the Gygaxian Great Wheel of the cosmos will return, as will the nine-fold alignment system and things like that.
We'll also almost certainly see the threefold hardback core of the game be continued. After that, though, things get interesting. I think everybody has just about realized that continuously publishing new core books is just splatbooks on steroids. Your game becomes unplayable a lot more quickly and players stop bothering to keep up. Still, it appears you can get a three-or-four-year good run on this model. If that's all you're interested in, then you’re golden.
What are the other options? WotC attempted an online subscription model. It didn't work, but that's in large part because they fumbled the launch. However, that strategy requires skills and knowledge that most gaming companies don't possess. Whoever wins the license won't have the resources of Hasbro and will likely be looking for a much cheaper strategy. (Unless it’s White Wolf. But I wouldn’t hold my breath on that one.)
I suspect that what we will see will steal a page from Paizo's success. We’ll have our core three books, one or two splatbooks a year, and something that looks an awful lot like the monthly Pathfinder product. It may be a bit more magazine and a bit less adventure module, but it will likely combine the successful formula of serial adventures, serial fiction, new monsters every issue, and high production values.
That being the case, we can expect the new rules to emphasize “long-term” play with characters advancing a level every two sessions or so, getting something new every level to play with, and campaigns lasting roughly a year. One-off play will likely be discouraged and it's doubtful we'll see any sort of organized play.
Likewise, I see the use of miniatures being downplayed. That business model hasn't flown for anybody yet. With it will vanish nearly all the positioning mechanics of 4E. Combat will be extremely abstract and simple. I suspect that we won’t see 4e’s exceptions-based rules, either. The result will look a lot more like 3e, but probably even simpler than that, with a stronger emphasis on combat and streamlined statblocks that don’t eat an entire page.
Unfortunately, I'm not expecting anything revolutionary. The game will continue to focus on combat, it will continue to use hit points and armor class will continue to be about how hard it is to hit. The game will continue to use classes and the core is likely to drop the Dragonborn race. Balance will be based on the set-piece combat encounter, and every class will be mappable with MMOG standards of class design. You'll still earn most of your experience points from killing things. In spite of this, I expect lots of appeals towards old-school nostalgia.